Many consumers are familiar with them term R-Value and how it relates to the effectiveness of a conventional attic insulation product. While foil insulation doesn't have an R-Value (you can read more about radiant barrier r-values here), it doesINCREASE the performance R-Value of your existing R-Value rated insulation.
We're often asked "What is the r-value of your RadiantGUARD radiant barrier?" The answer is simply zero because radiant barrier doesn't work like an R-Value rated product. So Exactly What Is An R-Value?